A new untethered jailbreak really needs to come out soon (let's hope the rumored one pans out). It feels like well executed jailbreak tweaks help keep Apple more willing to improve iOS and it's interaction. If nothing else it shows them ways ideas and features, whether original or inspired from other sources/OSes, can be made to fit well into iOS's design language and interaction model. It also shows them that users lust for something more than what they currently ship in terms of software.

It could of course be a coincidence that the longest jailbreak "draught" we've had coincides with the least innovative updates from Apple. There isn't necessarily a connection.